1. Field of the Invention
This invention relates generally to an improved weatherstrip system and material to prevent rain, snow, and air infiltration between the sides of a door or window and the frame or casing in which the door or window is mounted. More particularly, this invention relates to an improved weatherstrip for use between the door panels in a sliding glass door unit.
2. Description of the Prior Art
Most buildings constructed today have a significant number of movable or openable windows, doors, or similar portals into the interior of the building. Although such doors and windows are necessary from both a practical and aesthetic point of view, they allow weather elements from the outside to infiltrate into the building. In particular, they allow air infiltration into the interior of the building. For example, during the winter months, cold air infiltration around doors and windows into the interior of a house causes an increase in the heating costs for the house. In extreme cases, such air infiltration may require that the house have a heating system with a capacity which is larger than would otherwise be necessary. The same is true for hot air infiltration during the summer. Such infiltration is a factor which increases the costs of cooling a house with conventional air conditioning equipment.
Weatherstrip materials refer generically to the class of materials which is used to seal the joints or spaces between doors and windows and their respective casings to stop infiltration of air, rain, snow and the like. Weatherstrip materials have a variety of configurations depending upon which particular type of product they are associated with. One particular type of product utilizing weatherstrip material is that which is known as the Andersen Perma-Shield.RTM. Gliding Doors. The Perma-Shield.RTM. Gliding Door unit is a door unit for use generally adjacent the patio of a house. This door unit includes a door frame and two door panels. The door panels contain a glazing which comprises a double-paned safety insulating glass. One of the door panels is fixed inside the frame. The other door panel slides relatively thereto to open and close the door opening in the door unit. However, when the door panels are in their closed positions (i.e., the door opening is closed), the innermost frame members or the meeting stiles of each door panel are located generally adjacent one another and are spaced apart by a small gap. It has been conventional to place a weatherstrip material into this gap for sealing the door unit against air infiltration and the like.
The weatherstrip material previously used with the Perma-Shield.RTM. Gliding Door unit comprises what might be called a rigid interlocking type of weatherstrip. This weatherstrip is made from a rigid plastic material, such as rigid PVC. The cross-sectional configuration of this weatherstrip material was such that when the door panels were closed the weatherstrip members had various flanges or the like which would releasably interlock. However, in the Perma-Shield.RTM. glass door unit, the glass panes and door panels are quite long, wide and heavy. A common problem with such door panels is that the panels can bow or curve along the length thereof. Although the panels are fixed at the top and bottom of the glass door unit in the tracks for the door panels, the bow in the panels can easily increase or decrease the nominal thickness or gap between the panels at the center thereof. This decrease or increase in the thickness can be up to 50% of the nominal gap valve. When the nominal thickness is varied this much, the use of a rigid, interlocking type of weatherstrip presents certain problems, namely the door panels cannot be easily slid together to their closed position. In certain instances, trying to close the door panels with the nominal thickness having been increased or decreased will cause the rigid interlocking type of weatherstripping material to fracture or break. Such a fracture or break of course requires that the weatherstrip be replaced. Such replacement is burdensome, time-consuming and expensive.